Refrigerating apparatus with oil separating means



1956 E. J. KOCHER 3,283,532

REFRIGERATING APPARATUS WITH OIL SEPARATING MEANS Filed Sept. 25, 1965 nwENroz 52/ CH J KadHEe BY mam AT'To 2'4 EY5 United States Patent 3,283,532 REFRIGERATING APPARATUS WITH OIL SEPARATING MEANS Erich J. Kocher, Milwaukee, Wis., assignor to Vilter Manufacturing Corporation, Milwaukee, Wis., a corporation of Wisconsin Filed Sept. 23, 1965, Ser. No. 489,610 7 Claims. (Cl. 62473) The present invention relates generally to improvements in the art of refrigeration, and relates more particularly to the provision of a refrigerating system and apparatus employing improved instrumentalities for effectively separating oil from the refrigerant in the system and for returning the oil to the compressor.

Refrigerating systems of the type to which this invention relates commonly employ reciprocating compressors to provide high pressure refrigerant to the system in gaseous state. Normally, oil is employed in these compressors for cooling and lubricating purposes, the oil customarily being sprayed or splashed about the working parts. Inevitably, some of the compressor lubricating oil becomes entrained in the refrigerant passing through the compressor. If allowed to circulate, this oil reduces the efiiciency of the system by coating the various heat transfer surfaces of the system. The oil also causes maintenance problems by congeal-ing in the low temperature portions of the system and clogging check valves and other components.

It is therefore desirable to extract or separate the entrained oil from the refrigerant as quickly as possible after compression to minimize the effects of the oil on other parts of the system. Furthermore, it is desirable to remove the entrained oil while the refrigerant is in the gaseous state since less separating effort is required, the refrigerant is easier to handle, and differential pressures are existent in the gaseous state portion of the system for aiding the separation process. It is also desirable to provide a means for positively inducing the flow of the separated oil back to the compressor so as to remove it from the refrigerating system and prevent its further entrainment in the refrigerant.

A primary object of this invention is, therefore, to provide a refrigerating system having an improved means for extracting oil from the refrigerant immediately following compression and for positively inducing the return of residue oil back to the compressor.

Another object of the invention is to provide improved instrumentalities for inducing the extraction and return of residue oil to the compressor which employs high pressure gaseous refrigerant from the refrigeration system to accomplish the task.

A further object of the invention is to provide a refrigerant system having an improved device for positively inducing the extraction and return of oil to the compressor which includes a means for subjecting the oil to relatively high temperatures prior to its return to the compressor, to thereby further aid in the separation of the oil from the residue refrigerant and vice versa.

Another object of the invention is to provide a device for positively inducing the extraction and return of oil to the compressor, which device employs no moving parts and is furthermore simple and rugged in construction and requires no maintenance or adjustment for satisfactory operation even for extended periods.

A more detailed object of this invention is to provide a refrigerating system which includes an oil lubricated compressor providing high pressure gas to a discharge line, an oil separator in the high pressure discharge line communicating with the compressor for returning separated oil thereto, and means for inducing residue oil in the gas downstream of the oil separator to retum to the oil sepa- 3,283,532 Patented Nov. 8, 1966 rator from which it is returned to the compressor along with the initially separated oil.

Additional objects and advantages of the invention will become apparent from the following specification and drawing, forming a part thereof, in which:

FIGURE 1 is a diagrammatic part sectional view illustrating the components of a typical refrigerating system embodying the invention; and

FIGURE 2 is a fragmentary part sectional view of the oil separating portion of the system and including the means for inducing return of residue oil from a point upstream of the separator.

Referring to the drawing, the typical refrigerating system shown therein comprises, in general, a compressor 4 having an inlet or suction conduit 6 leading thereto and an outlet or high pressure discharge line 8, 9 leading therefrom; a condenser 10 disposed in the high pressure discharge line 9; a receiver 12 communicating with condenser 10 through conduit 14; and an evaporator or cooling coil 16 having its inlet end 18 in communication with receiver 12 and its outlet end 29 in communication with compressor 4 by way of suction conduit 6.

In accordance with the present invention, an oil separator 44 is imposed in the high pressure discharge line 8, 9 between the compressor 4 and the condenser 10 for initially separating entrained oil from the refrigerant. While the use of an oil separator at this point in the system is not, of itself, new, additional means, associated with the separator 44, for removing any residue oil from the refrigerant downstream of the separator and for inducing the return of such residue refrigerant to the separator and then back to the compressor has been provided, as will hereinafter more fully appear.

Compressor 4 may be of a conventional, oil lubricated reciprocating piston type, and the condenser 10 may be of the so-called shell and tube type, as shown, in which cooling water supplied to conduit connection 22 is circulated through a plurality of tubes 24 traversing the shell 26 between heads 28 and 30. The high pressure discharge line 8 also includes the usual one-way, nonreturn check valve 31 therein and a similar check valve 32 is interposed in the gravity feed line 14 between condenser 10 and the receiver 12. The receiver is also provided with the customary liquid level indicating gauge 34, and the usual expansion valve 36 is provided in the inlet to the evaporator 16.

For purposes of illustration, the condenser 10 has been shown and described herein as being formed with an oil separating section 38 incorporated directly in the inlet end thereof for extracting residue oil from the refrigerant downstream of the oil separator 44. However, it should be understood that such secondary oil extraction means may be of any suitable type and may, in fact, simply be in the nature of a header such as might be imposed be tween a desuperheating coil and the condenser coils in another typical embodiment.

As illustrated, however, the condenser 10 includes an oil separating section 38 at its inlet end, such oil separating sectionbeing formed by a plurality of spaced baflles 40 and 42, providing a circuitous path of travel for the gaseous refrigerant discharged by compressor 4 and containing residue oil not removed in the initial separation zone 44. As the gaseous refirgerant and the entrained residue oil enter the condenser 10, they impinge upon the depending baflle 40 and are directed downwardly about cooling tubes 24. The gas'ous refrigerant and entrained residue oil next impinge upon the upwardly projecting baffle 42 and are caused to flow in an upward direction about cooling tubes 24 before leaving section 38 and entering the main body of shell 26. By reason of the impingement of the refrigerant vapor and residue oil upon the baffles and the prolonged period of cooling afforded during the travel of the vapor and oil in its circuitous path about the tubes 24 Within section 38, the oil is caused to effectively separate from the gaseous refrigerant in this section and such extracted residue oil is confined to the bottom of section 38 by baffle 42.

To provide for the return of the extracted residue oil from section 38 of the condenser to the compressor 4 and for further extraction of any residue refrigerant from the oil and the return thereof to the system, a residue oil return conduit 54 communicate the sump of section 38 with the upper portion 46 of the primary oil separator 44. As illustnated, the discharge line 8 leading from the high pressure side of the compressor 4 extends downwardly into the upper section 46 of separator 44 and terminates with a filter 48. The high pressure line 9 leading to condenser 10' likewise extends into the upper section 46 of the separator 44 and terminates with a similar filter 49. A bafile 50 extending downwardly across the section 46 separates the lines 8 and 9 and causes a circuitous flow in the separator 44 above the sump portion 58 thereof. In addition, the discharge line 8 includes a restriction or venturi 52 Within the throat portion extending into the separator 44.

In accordance with the invention, a conduit 54 is interposed between the sump of the oil separating or extraction section 38 of the condenser 10 and the throat Oif ventu-ri 52 in the line 8 to separator 44. As shown, the conduit 54 is preferably affixed in heat transfer relationship with discharge line 8 as by soldering, welding or fastening the same along a medial portion 56 with an adhesive of high heat conductivity on or about the discharge line 8. By this arrangement, any residue oil extracted in section 38 of the condenser 10 is induced to flow through the conduit 54 by the action of the high pressure gases passing through the venturi portion 52 of line 8. Furthermore, the exposure of the oil passing through the conduit 54 to the heat existing in the high pressure discharge line 8 within the area 56 aids in extracting any residue refrigerant from the oil :as it enters the upper section 46 of the separator 44.

As shown, the bottom of the separator 44 contains a sump 58 for receiving the extracted oil while the gaseous refrigerant entering the section 46 of separator 44 returns to the system via line 9. The level of the oil in sump 48 is controlled by a float valve 66 or the like which permits the oil to flow through a conduit 62 back to the crankcase section of the compressor 4.

Reviewing the operation, compressor 4 provides high pressure gaseous refrigerant to the discharge line 8. This gas will be of increased temperature due to its compression. Additionally, the gas will inevitably have oil from the compressor 4 entrained therein. The gas and entrained oil flows from compressor 4 through the discharge line 8 and venturi 52 through filter 48 and around the bafiie 50 of the primary separator 44 and then through filter 49 and high pressure line 9 to the inlet of condenser 10. As the high pressure gas passes through the separator 44, much of the oil is separated therefrom and is returned to the compressor 4 from the sump 48. However, the gas passing through line 9 to the condenser 10 normally contains some residue oil, and as previously described, the inlet of condenser 10 includes section 38 which extracts the entrained residue oil from the gaseous refrigerant prior to condensing the refrigerant to a liquid. This separated oil is then returned via conduit 54 to separator 44 and also collects in the bottom section 48 thereof for return to the compressor. The liquid refrigerant, of course, continues through the condenser '10 and then past check valve 32 and circulates through through conduit 54 and into venturi 52 and discharge line 8. As the entire quantity of gas discharged from compressor 4 passes through venturi 52, the reduction in pressure in discharge line 8 caused by the venturi is of sufficient magnitude toinduce the removal of all the extracted oil from the bottom of section 38. The separated oil then falls into sump 58 of housing 46 and subsequently flows, as needed, through conduit 62 to condenser 4 under control of the float valve 60.

It will be appreciated from the foregoing description that the refrigerating system and apparatus of the present invention provides for the effective removal of entrained oil from the refrigerant as soon after compression as possible, thereby minimizing the deleterious ettects on the system from the oil. Further, the oil is effectively returned to the compressor after its removal from the refrigerant, and the removal and return of the oil occurs while both the oil and the refrigerant are hot from compression, thereby aiding in the separation of the oil and the refrigerant and allowing the oil to flow freely through conduit 54 and venturi 52. As previously mentioned, conduit 54 is preferably affixed in heat transfer relation with discharge line 8 from compressor 4 to further heat the oil and any entrained refrigerant. This also serves to complete the separation of the oil from v the refrigerant and vice versa,

Since modification-s and alterations may be made to the present invention, it is intended to cover in the appended claims all such variations and modifications as fall within the true spirit and scope of the invention.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention:

I claim:

1. In a refrigerating system having an oil lubricated compressor providing high pressure gas to a discharge line communicating with a condenser for distribution in the system, an oil separator interposed in the high pressure discharge line in open communication therewith for initially separating entrained oil from the high pressure gas, said separator communicating with the compressor for returning separated oil thereto, and means downstream of said separator and associated with the inlet to the condenser for separating residue oil from the gas, said residue oil separating means communicating with said initial oil separator through the high pressure discharge line to induce the residue oil to return thereto.

2. A refrigerating system according to claim 1, wherein the means for inducing return of residue oil to the initial oil separator includes a venturi in the high pressure discharge line.

3. A refrigerating system according to claim 1, wherein means is also provided for subjecting the residue oil returning to the initial oil separator to heat for the extraction of any residue refrigerant therefrom.

4. A refrigerating system according to claim 3, wherein the means for subjecting the residue return oil to heat includes a section of the high pressure discharge line.

5. In a refrigerating system including an oil lubricated compressor providing high pressure gas to a discharge line communicating with a condenser, an initial oil separator interposed in the high pressure discharge line be tween the compressor and the condenser for extracting oil from the high pressure gas as it flows through the discharge line, means for returning the extracted oil from said separator to the compressor, means interposed between said initial oil separator and the main body portion of the condenser for extracting residue oil from the high pressure gas downstream of the initial oil separator and conduit means communicating with said residue oil extracting means :and wit-h the high pressure discharge line for inducing return of such extracted residue oil to the initial separator.

6. A refrigerating system according to claim 5, wherein the means for inducing flow through the conduit includes a venturi in the high pressure discharge line adjacent the entrance thereof to the initial oil separator.

7. A refrigerating system according to claim 5, wherein the oil return conduit is placed in heat exchange relation with -a portion of the high pressure discharge line to subject the returning residue oil to heat.

References Cited by the Examiner UNITED STATES PATENTS 1,718,683 6/1929 Carrier 6284 X 1,835,081 12/1931 Pollard 62473 2,900,801 8/1959 Honnegger 62473 X 6 FOREIGN PATENTS 576,921 4/1946 Great Britain.

ROBERT A. OLEARY, Primary Examiner.

5 W. E. WAYNER, Assistant Examiner. 

1. IN A REFRIGERATING SYSTEM HAVING AN OIL LUBRICATED COMPRESSOR PROVIDING HIGH PRESSURE GAS TO A DISCHARGE LINE COMMUNICATING WITH A CONDENSER FOR DISTRIBUTION IN THE SYSTEM, AN OIL SEPARATOR INTERPOSED IN THE HIGH PRESSURE DISCHARGE LINE IN OPEN COMMUNICATION THEREWITH FOR INITIALLY SEPARATING ENTRAINED OIL FROM THE HIGH PRESSURE GAS, SAID SEPARATOR COMMUNICATING WITH THE COMPRESSOR FOR RETURNING SEPARATED OIL THERETO, AND MEANS DOWN- 